Indoor Winter Gardening

Give plants the right lights, and they’ll grow in any season

By Dr. Francis Gouin

Plants don’t like freezing temperatures any more than we do. But many will be perfectly happy to grow indoors, encouraged by fluorescent lights.
Under lights, you can grow plants, including vegetables, up to 10 inches tall.
Success depends on choosing the right setup. Many systems are on the market, but not all are of equal quality. Beware of those made entirely of chrome-plated steel. They are susceptible to rusting from the fertilizers used for growing. Chrome-plated shelves and trays are especially vulnerable. Stainless steel or plastic-coated shelves and trays will outlast all others.
Nearly all the lighting fixtures are designed to hold Grow-lux fluorescent bulbs. Grow-lux lights emit both the blue and red rays of light, and both are necessary for photosynthesis and flower production. For maximum effectiveness, the uppermost foliage of the plants must be placed within inches of the light source. Grow-lux lights are recognized for their light quality and not for their light intensity. To improve the light intensity of your growing chamber, consider including a warm white fluorescent bulb for every two Grow-Lux lights in the light bank. Adding warm white bulbs is especially important when growing tall plants or plants with varying heights. Only warm white fluorescent bulbs emit the red light essential for photosynthesis with sufficient intensity to penetrate the foliage to a depth of eight to 10 inches. Cool white fluorescent bulbs emit only low levels of blue light, which is not as essential for photosynthesis as red light.
High intensity lighting fixtures can be built using a combination of power-groove fluorescent tubes and 60-watt incandescent bulbs. This sort of setup is used to supply lighting in commercial growth chambers. However, these power-groove fluorescent tubes generate so much heat that fans must be used to circulate the air.
Meeting the irrigation needs of plants growing under artificial lights can be challenging. Plants growing under Glor-lux lights require less water than plants growing under warm white fluorescent lights due to cooler rooting media temperatures. Because the red waves from warm white fluorescent bulbs penetrate deeper, rooting media are warmer and dry out faster.
Avoid overcrowding plants under artificial lights. As the plants increase in size, provide additional space for them. A good rule of thumb is to never allow the foliage of one plant to touch that of an adjoining plant. Allowing the plants to grow under crowded conditions will give you tall spindly plants with weak stems and yellowing leaves at the bottom.